The present invention relates to lubricating compositions, and more particularly to an emulsion of a lubricating oil and particles of polytetrafluoroethylene substantially evenly dispersed and suspended therein. The present invention further relates to a process for manufacturing this lubricating composition, and still further to a system for manufacturing this lubricating composition.
Lubricating compositions of oil and polytetrafluoroethylene, and various processes for making them, are known. For example, U.S. Pat. No. 3,247,116, issued on Apr. 19, 1966 to Victor G. Reiling, is directed to a lubricating composition of powdered, degraded polytetrafluoroethylene resin in a liquid vehicle wherein the polytetrafluoroethylene resin is degraded by heating the resin to a temperature of between 785.degree. F. and 880.degree. F. for a period of about two hours before blending it with a liquid carrier.
U.S. Pat. No. 3,933,656, issued on Jan. 20, 1976 to Franklin G. Reick, is directed to a lubricating oil additive composed of a commercially available aqueous dispersion of sub-micron polytetrafluoroethylene particles and a charge neutralizing agent, such as a silane. The silane allegedly stabilizes the dispersion to prevent agglomeration and coagulation of the polytetrafluorethylene particles. This dispersion is mixed with a quantity of lubricating oil, which functions here as a carrier, to produce the additive which is to be added to the lubricating oil in the crankcase of an internal combustion engine. The polytetrafluoroethylene has a tendency to settle, but redispersion is effected with the mildest agitation, taking care to avoid violent agitation since this will cause irreversible coagulation.
U.S. Pat. No. 4,224,173, issued on Sept. 23, 1980 to Franklin G. Reick, is directed to a lubricant formed of a commercially available aqueous dispersion of sub-micron polytetrafluoroethylene particles to which a fluro surfactant is added to neutralize the surface charge on the particles to prevent agglomeration. The stabilized aqueous dispersion is added to a lubricating oil, which acts as a carrier, and the mixture is subjected to a turbulent treatment to disperse the colloidal polytetrofluoroethylene in the lubricating oil carrier. A polymeric dispersant is also added to promote homogenization. An absorbent surfactant, which is appropriate to the metals to be lubricated, is added to the homogenized emulsion to promote adhesion of the lubricant to the surfaces of the parts to be lubricated.
The processes heretofore known to me do not produce a lubricating composition in which the polytetrafluoroethylene is adequately suspended therethrough such as to provide a commercially desirable product with a sufficiently long shelf life. Furthermore, these heretofore known processes require steps which are necessarily time consuming and therefore commercially expensive, or which involve the addition of extraneous materials to accomplish stability of the polytetrafluoroethylene in suspension which materials increase the cost of manufacture while contributing little, or nothing to the lubrication properties of the composition.